Wood flooring is used extensively for truck trailers, railroad box cars, and shipping containers sometimes known as cargo containers. The flooring for semi-trailers, railroad box cars, and shipping containers consists of lengths of wooden strips, typically measuring about 1 inch in width and 1 and 1/4 inch in depth. The wooden strips are joined endwise to the desired length (for a truck trailer, typically about 40 feet or more), and the formed strips are laid longitudinally side by side, that is in edge-to-edge abutment, and sealed at the seams to form a one foot wide flooring plank. The flooring planks are then joined along the longitudinal edges, usually by tongue-and-groove, to form a floor, which for a truck trailer is about eight feet or more in width.
In a wood flooring of this construction, the seams have a tendency to separate, and water from beneath the flooring can enter the interior of the trailer, box car, or shipping container through the splits, joints, or openings, which can damage the goods being transported or shipped. Separation at the seams of the wood strips or planks is aggravated by reason of normal use, such as occurs when loading or unloading or from jarring during transportation. Further, water on the interior of the truck trailer, box car, or shipping container can warp the wood flooring causing even greater separation of the wood strips or planks. In order to inhibit water from entering the interior, the underside of the flooring is spray coated with various organic sealants, which now has been discontinued due to environmental problems. The industry now uses a water-base acrylic sealant. It is important, however, that the wood be allowed to breathe, and that vapor be transmitted though the wood flooring. The problem with the acrylic sealants is these materials are impervious to vapor. In the event water is carried unintentionally into the interior, such as snow carried along with the goods being shipped or when loading during a rainstorm, this water can seep into the flooring and cannot pass through the flooring even as vapor because of the impervious barrier. Also, the acrylic, when first applied, frequently does not fill all of the cracks or openings in the floor, or the wood can expand and contract thereby forming an opening and allowing water to enter the trailer. Additionally, the acrylic is brittle and tends to crack, thereby forming an opening which allows for the entrance of water.
There are a number of patents relating to film insulating and barrier materials, including insulating materials for vehicle panels and flooring. U.S. Pat. No. 3,788,682 discloses a trailer construction having side panels 12 comprising a core 13 of plywood or the like, and a coating of plastic-containing material on the opposite surfaces. The coating is described as a fiber reinforced resin, such as a polyester of polyether resin reinforced with glass fibers, which is bonded to the core by heat curing and pressure. The object of the invention is to provide a body panel in which the entrapment of air between the plastic coating and the core is eliminated.
A floor construction is disclosed in U.S. Pat. No. 2,149,026 comprising a concrete sub-floor, a mastic coating 7 conforming to the surface of the concrete, and a wooden flooring 2. The mastic pad is described as oleaginous (oily material), and specifically as asphalt, asphaltic base composition, or as an asphalt cement. This construction protects the flooring from adverse moisture conditions, both from within the room and from moisture migrating from the concrete sub-floor.
Waterproofing paper, fabric or other materials used in conjunction with lumber construction are disclosed in U.S. Pat. Nos. 1,655,699; 2,070,479; 2,712,863; and 4,146,662. Thus, U.S. Pat. No. 1,655,699 discloses a composite lumber slab comprising two layers of wooden blocks A and B interposed with a layer of fabric C saturated with glue. In U.S. Pat. No. 4,146,662, there is disclosed a solid core door having a hardwood veneer 16 coated on each side with a resin impregnated overlay 14. In U.S. Pat. No. 2,070,479, a layer of felt 24 is cemented to the flooring 25 to provide sound and heat proofing, and the wall panels 40 are provided with a layer of waterproof paper 39. The prefabricated bathroom unit disclosed in U.S. Pat. No. 2,712,863 includes a floor 50 covered on the upper surface with a waterproof material 54, such as aluminum, overlayed with a sheet of linoleum 56.
No reference is known to the inventor disclosing or relating to a useful and practicalable protected wood flooring for a truck trailer, railroad box car, or shipping container. This invention has, therefore, as its purpose to provide a wood flooring that is isolated or protected from the ingress of liquid from the undersurface.
Another object of the invention is to provide a barrier means for such flooring that is impermeable to liquid and permeable to vapor.
It is still another object of this invention to provide such a barrier means that is breathable so as to prevent water from entering the interior surface of the flooring but allowing vapor to pass, thereby substantially eliminating warpage of the flooring caused by water entering and accumulating on the interior side of the flooring.
Yet another object of the invention is to provide such a barrier means that will allow for water situated or confined interiorly to egress as vapor.
It is still another object of this invention to provide such a barrier means that is breathable so as to prevent water from entering the interior surface of the flooring but allowing vapor to pass, thereby substantially eliminating damage to the goods being shipped caused by water on the interior side of the flooring.